Percona-Server-5.6.14-rel62.0 merge

support ha_innodb.so as a dynamic plugin.
* remove obsolete *,innodb_plugin.rdiff files
* s/--plugin-load=/--plugin-load-add=/
* MYSQL_PLUGIN_IMPORT glob_hostname[]
* use my_error instead of push_warning_printf(ER_DEFAULT)
* don't use tdc_size and tc_size in a module

update test cases (XtraDB is 5.6.14, InnoDB is 5.6.10)
* copy new tests over
* disable some tests for (old) InnoDB
* delete XtraDB tests that no longer apply

small compatibility changes:
* s/HTON_EXTENDED_KEYS/HTON_SUPPORTS_EXTENDED_KEYS/
* revert unnecessary InnoDB changes to make it a bit closer to the upstream

fix XtraDB to compile on Windows (both as a static and a dynamic plugin)

disable XtraDB on Windows (deadlocks) and where no atomic ops are available (e.g. CentOS 5)


storage/innobase/handler/ha_innodb.cc:
  revert few unnecessary changes to make it a bit closer to the original InnoDB
storage/innobase/include/univ.i:
  correct the version to match what it was merged from

1 files changed, 1656 insertions, 0 deletions

diff --git a/storage/xtradb/trx/trx0rec.cc b/storage/xtradb/trx/trx0rec.cc
new file mode 100644
index 00000000000..a698b37c2a6
--- /dev/null
+++ b/storage/xtradb/trx/trx0rec.cc
@@ -0,0 +1,1656 @@
+/*****************************************************************************
+
+Copyright (c) 1996, 2012, Oracle and/or its affiliates. All Rights Reserved.
+
+This program is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free Software
+Foundation; version 2 of the License.
+
+This program is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA
+
+*****************************************************************************/
+
+/**************************************************//**
+@file trx/trx0rec.cc
+Transaction undo log record
+
+Created 3/26/1996 Heikki Tuuri
+*******************************************************/
+
+#include "trx0rec.h"
+
+#ifdef UNIV_NONINL
+#include "trx0rec.ic"
+#endif
+
+#include "fsp0fsp.h"
+#include "mach0data.h"
+#include "trx0undo.h"
+#include "mtr0log.h"
+#ifndef UNIV_HOTBACKUP
+#include "dict0dict.h"
+#include "ut0mem.h"
+#include "read0read.h"
+#include "row0ext.h"
+#include "row0upd.h"
+#include "que0que.h"
+#include "trx0purge.h"
+#include "trx0rseg.h"
+#include "row0row.h"
+
+/*=========== UNDO LOG RECORD CREATION AND DECODING ====================*/
+
+/**********************************************************************//**
+Writes the mtr log entry of the inserted undo log record on the undo log
+page. */
+UNIV_INLINE
+void
+trx_undof_page_add_undo_rec_log(
+/*============================*/
+	page_t* undo_page,	/*!< in: undo log page */
+	ulint	old_free,	/*!< in: start offset of the inserted entry */
+	ulint	new_free,	/*!< in: end offset of the entry */
+	mtr_t*	mtr)		/*!< in: mtr */
+{
+	byte*		log_ptr;
+	const byte*	log_end;
+	ulint		len;
+
+	log_ptr = mlog_open(mtr, 11 + 13 + MLOG_BUF_MARGIN);
+
+	if (log_ptr == NULL) {
+
+		return;
+	}
+
+	log_end = &log_ptr[11 + 13 + MLOG_BUF_MARGIN];
+	log_ptr = mlog_write_initial_log_record_fast(
+		undo_page, MLOG_UNDO_INSERT, log_ptr, mtr);
+	len = new_free - old_free - 4;
+
+	mach_write_to_2(log_ptr, len);
+	log_ptr += 2;
+
+	if (log_ptr + len <= log_end) {
+		memcpy(log_ptr, undo_page + old_free + 2, len);
+		mlog_close(mtr, log_ptr + len);
+	} else {
+		mlog_close(mtr, log_ptr);
+		mlog_catenate_string(mtr, undo_page + old_free + 2, len);
+	}
+}
+#endif /* !UNIV_HOTBACKUP */
+
+/***********************************************************//**
+Parses a redo log record of adding an undo log record.
+@return	end of log record or NULL */
+UNIV_INTERN
+byte*
+trx_undo_parse_add_undo_rec(
+/*========================*/
+	byte*	ptr,	/*!< in: buffer */
+	byte*	end_ptr,/*!< in: buffer end */
+	page_t*	page)	/*!< in: page or NULL */
+{
+	ulint	len;
+	byte*	rec;
+	ulint	first_free;
+
+	if (end_ptr < ptr + 2) {
+
+		return(NULL);
+	}
+
+	len = mach_read_from_2(ptr);
+	ptr += 2;
+
+	if (end_ptr < ptr + len) {
+
+		return(NULL);
+	}
+
+	if (page == NULL) {
+
+		return(ptr + len);
+	}
+
+	first_free = mach_read_from_2(page + TRX_UNDO_PAGE_HDR
+				      + TRX_UNDO_PAGE_FREE);
+	rec = page + first_free;
+
+	mach_write_to_2(rec, first_free + 4 + len);
+	mach_write_to_2(rec + 2 + len, first_free);
+
+	mach_write_to_2(page + TRX_UNDO_PAGE_HDR + TRX_UNDO_PAGE_FREE,
+			first_free + 4 + len);
+	ut_memcpy(rec + 2, ptr, len);
+
+	return(ptr + len);
+}
+
+#ifndef UNIV_HOTBACKUP
+/**********************************************************************//**
+Calculates the free space left for extending an undo log record.
+@return	bytes left */
+UNIV_INLINE
+ulint
+trx_undo_left(
+/*==========*/
+	const page_t*	page,	/*!< in: undo log page */
+	const byte*	ptr)	/*!< in: pointer to page */
+{
+	/* The '- 10' is a safety margin, in case we have some small
+	calculation error below */
+
+	return(UNIV_PAGE_SIZE - (ptr - page) - 10 - FIL_PAGE_DATA_END);
+}
+
+/**********************************************************************//**
+Set the next and previous pointers in the undo page for the undo record
+that was written to ptr. Update the first free value by the number of bytes
+written for this undo record.
+@return	offset of the inserted entry on the page if succeeded, 0 if fail */
+static
+ulint
+trx_undo_page_set_next_prev_and_add(
+/*================================*/
+	page_t*		undo_page,	/*!< in/out: undo log page */
+	byte*		ptr,		/*!< in: ptr up to where data has been
+					written on this undo page. */
+	mtr_t*		mtr)		/*!< in: mtr */
+{
+	ulint		first_free;	/*!< offset within undo_page */
+	ulint		end_of_rec;	/*!< offset within undo_page */
+	byte*		ptr_to_first_free;
+					/* pointer within undo_page
+					that points to the next free
+					offset value within undo_page.*/
+
+	ut_ad(ptr > undo_page);
+	ut_ad(ptr < undo_page + UNIV_PAGE_SIZE);
+
+	if (UNIV_UNLIKELY(trx_undo_left(undo_page, ptr) < 2)) {
+
+		return(0);
+	}
+
+	ptr_to_first_free = undo_page + TRX_UNDO_PAGE_HDR + TRX_UNDO_PAGE_FREE;
+
+	first_free = mach_read_from_2(ptr_to_first_free);
+
+	/* Write offset of the previous undo log record */
+	mach_write_to_2(ptr, first_free);
+	ptr += 2;
+
+	end_of_rec = ptr - undo_page;
+
+	/* Write offset of the next undo log record */
+	mach_write_to_2(undo_page + first_free, end_of_rec);
+
+	/* Update the offset to first free undo record */
+	mach_write_to_2(ptr_to_first_free, end_of_rec);
+
+	/* Write this log entry to the UNDO log */
+	trx_undof_page_add_undo_rec_log(undo_page, first_free,
+					end_of_rec, mtr);
+
+	return(first_free);
+}
+
+/**********************************************************************//**
+Reports in the undo log of an insert of a clustered index record.
+@return	offset of the inserted entry on the page if succeed, 0 if fail */
+static
+ulint
+trx_undo_page_report_insert(
+/*========================*/
+	page_t*		undo_page,	/*!< in: undo log page */
+	trx_t*		trx,		/*!< in: transaction */
+	dict_index_t*	index,		/*!< in: clustered index */
+	const dtuple_t*	clust_entry,	/*!< in: index entry which will be
+					inserted to the clustered index */
+	mtr_t*		mtr)		/*!< in: mtr */
+{
+	ulint		first_free;
+	byte*		ptr;
+	ulint		i;
+
+	ut_ad(dict_index_is_clust(index));
+	ut_ad(mach_read_from_2(undo_page + TRX_UNDO_PAGE_HDR
+			       + TRX_UNDO_PAGE_TYPE) == TRX_UNDO_INSERT);
+
+	first_free = mach_read_from_2(undo_page + TRX_UNDO_PAGE_HDR
+				      + TRX_UNDO_PAGE_FREE);
+	ptr = undo_page + first_free;
+
+	ut_ad(first_free <= UNIV_PAGE_SIZE);
+
+	if (trx_undo_left(undo_page, ptr) < 2 + 1 + 11 + 11) {
+
+		/* Not enough space for writing the general parameters */
+
+		return(0);
+	}
+
+	/* Reserve 2 bytes for the pointer to the next undo log record */
+	ptr += 2;
+
+	/* Store first some general parameters to the undo log */
+	*ptr++ = TRX_UNDO_INSERT_REC;
+	ptr += mach_ull_write_much_compressed(ptr, trx->undo_no);
+	ptr += mach_ull_write_much_compressed(ptr, index->table->id);
+	/*----------------------------------------*/
+	/* Store then the fields required to uniquely determine the record
+	to be inserted in the clustered index */
+
+	for (i = 0; i < dict_index_get_n_unique(index); i++) {
+
+		const dfield_t*	field	= dtuple_get_nth_field(clust_entry, i);
+		ulint		flen	= dfield_get_len(field);
+
+		if (trx_undo_left(undo_page, ptr) < 5) {
+
+			return(0);
+		}
+
+		ptr += mach_write_compressed(ptr, flen);
+
+		if (flen != UNIV_SQL_NULL) {
+			if (trx_undo_left(undo_page, ptr) < flen) {
+
+				return(0);
+			}
+
+			ut_memcpy(ptr, dfield_get_data(field), flen);
+			ptr += flen;
+		}
+	}
+
+	return(trx_undo_page_set_next_prev_and_add(undo_page, ptr, mtr));
+}
+
+/**********************************************************************//**
+Reads from an undo log record the general parameters.
+@return	remaining part of undo log record after reading these values */
+UNIV_INTERN
+byte*
+trx_undo_rec_get_pars(
+/*==================*/
+	trx_undo_rec_t*	undo_rec,	/*!< in: undo log record */
+	ulint*		type,		/*!< out: undo record type:
+					TRX_UNDO_INSERT_REC, ... */
+	ulint*		cmpl_info,	/*!< out: compiler info, relevant only
+					for update type records */
+	bool*		updated_extern,	/*!< out: true if we updated an
+					externally stored fild */
+	undo_no_t*	undo_no,	/*!< out: undo log record number */
+	table_id_t*	table_id)	/*!< out: table id */
+{
+	byte*		ptr;
+	ulint		type_cmpl;
+
+	ptr = undo_rec + 2;
+
+	type_cmpl = mach_read_from_1(ptr);
+	ptr++;
+
+	*updated_extern = !!(type_cmpl & TRX_UNDO_UPD_EXTERN);
+	type_cmpl &= ~TRX_UNDO_UPD_EXTERN;
+
+	*type = type_cmpl & (TRX_UNDO_CMPL_INFO_MULT - 1);
+	*cmpl_info = type_cmpl / TRX_UNDO_CMPL_INFO_MULT;
+
+	*undo_no = mach_ull_read_much_compressed(ptr);
+	ptr += mach_ull_get_much_compressed_size(*undo_no);
+
+	*table_id = mach_ull_read_much_compressed(ptr);
+	ptr += mach_ull_get_much_compressed_size(*table_id);
+
+	return(ptr);
+}
+
+/**********************************************************************//**
+Reads from an undo log record a stored column value.
+@return	remaining part of undo log record after reading these values */
+static
+byte*
+trx_undo_rec_get_col_val(
+/*=====================*/
+	byte*	ptr,	/*!< in: pointer to remaining part of undo log record */
+	byte**	field,	/*!< out: pointer to stored field */
+	ulint*	len,	/*!< out: length of the field, or UNIV_SQL_NULL */
+	ulint*	orig_len)/*!< out: original length of the locally
+			stored part of an externally stored column, or 0 */
+{
+	*len = mach_read_compressed(ptr);
+	ptr += mach_get_compressed_size(*len);
+
+	*orig_len = 0;
+
+	switch (*len) {
+	case UNIV_SQL_NULL:
+		*field = NULL;
+		break;
+	case UNIV_EXTERN_STORAGE_FIELD:
+		*orig_len = mach_read_compressed(ptr);
+		ptr += mach_get_compressed_size(*orig_len);
+		*len = mach_read_compressed(ptr);
+		ptr += mach_get_compressed_size(*len);
+		*field = ptr;
+		ptr += *len;
+
+		ut_ad(*orig_len >= BTR_EXTERN_FIELD_REF_SIZE);
+		ut_ad(*len > *orig_len);
+		/* @see dtuple_convert_big_rec() */
+		ut_ad(*len >= BTR_EXTERN_FIELD_REF_SIZE);
+
+		/* we do not have access to index->table here
+		ut_ad(dict_table_get_format(index->table) >= UNIV_FORMAT_B
+		      || *len >= col->max_prefix
+		      + BTR_EXTERN_FIELD_REF_SIZE);
+		*/
+
+		*len += UNIV_EXTERN_STORAGE_FIELD;
+		break;
+	default:
+		*field = ptr;
+		if (*len >= UNIV_EXTERN_STORAGE_FIELD) {
+			ptr += *len - UNIV_EXTERN_STORAGE_FIELD;
+		} else {
+			ptr += *len;
+		}
+	}
+
+	return(ptr);
+}
+
+/*******************************************************************//**
+Builds a row reference from an undo log record.
+@return	pointer to remaining part of undo record */
+UNIV_INTERN
+byte*
+trx_undo_rec_get_row_ref(
+/*=====================*/
+	byte*		ptr,	/*!< in: remaining part of a copy of an undo log
+				record, at the start of the row reference;
+				NOTE that this copy of the undo log record must
+				be preserved as long as the row reference is
+				used, as we do NOT copy the data in the
+				record! */
+	dict_index_t*	index,	/*!< in: clustered index */
+	dtuple_t**	ref,	/*!< out, own: row reference */
+	mem_heap_t*	heap)	/*!< in: memory heap from which the memory
+				needed is allocated */
+{
+	ulint		ref_len;
+	ulint		i;
+
+	ut_ad(index && ptr && ref && heap);
+	ut_a(dict_index_is_clust(index));
+
+	ref_len = dict_index_get_n_unique(index);
+
+	*ref = dtuple_create(heap, ref_len);
+
+	dict_index_copy_types(*ref, index, ref_len);
+
+	for (i = 0; i < ref_len; i++) {
+		dfield_t*	dfield;
+		byte*		field;
+		ulint		len;
+		ulint		orig_len;
+
+		dfield = dtuple_get_nth_field(*ref, i);
+
+		ptr = trx_undo_rec_get_col_val(ptr, &field, &len, &orig_len);
+
+		dfield_set_data(dfield, field, len);
+	}
+
+	return(ptr);
+}
+
+/*******************************************************************//**
+Skips a row reference from an undo log record.
+@return	pointer to remaining part of undo record */
+UNIV_INTERN
+byte*
+trx_undo_rec_skip_row_ref(
+/*======================*/
+	byte*		ptr,	/*!< in: remaining part in update undo log
+				record, at the start of the row reference */
+	dict_index_t*	index)	/*!< in: clustered index */
+{
+	ulint	ref_len;
+	ulint	i;
+
+	ut_ad(index && ptr);
+	ut_a(dict_index_is_clust(index));
+
+	ref_len = dict_index_get_n_unique(index);
+
+	for (i = 0; i < ref_len; i++) {
+		byte*	field;
+		ulint	len;
+		ulint	orig_len;
+
+		ptr = trx_undo_rec_get_col_val(ptr, &field, &len, &orig_len);
+	}
+
+	return(ptr);
+}
+
+/**********************************************************************//**
+Fetch a prefix of an externally stored column, for writing to the undo log
+of an update or delete marking of a clustered index record.
+@return	ext_buf */
+static
+byte*
+trx_undo_page_fetch_ext(
+/*====================*/
+	byte*		ext_buf,	/*!< in: buffer to hold the prefix
+					data and BLOB pointer */
+	ulint		prefix_len,	/*!< in: prefix size to store
+					in the undo log */
+	ulint		zip_size,	/*!< compressed page size in bytes,
+					or 0 for uncompressed BLOB  */
+	const byte*	field,		/*!< in: an externally stored column */
+	ulint*		len)		/*!< in: length of field;
+					out: used length of ext_buf */
+{
+	/* Fetch the BLOB. */
+	ulint	ext_len = btr_copy_externally_stored_field_prefix(
+		ext_buf, prefix_len, zip_size, field, *len);
+	/* BLOBs should always be nonempty. */
+	ut_a(ext_len);
+	/* Append the BLOB pointer to the prefix. */
+	memcpy(ext_buf + ext_len,
+	       field + *len - BTR_EXTERN_FIELD_REF_SIZE,
+	       BTR_EXTERN_FIELD_REF_SIZE);
+	*len = ext_len + BTR_EXTERN_FIELD_REF_SIZE;
+	return(ext_buf);
+}
+
+/**********************************************************************//**
+Writes to the undo log a prefix of an externally stored column.
+@return	undo log position */
+static
+byte*
+trx_undo_page_report_modify_ext(
+/*============================*/
+	byte*		ptr,		/*!< in: undo log position,
+					at least 15 bytes must be available */
+	byte*		ext_buf,	/*!< in: a buffer of
+					DICT_MAX_FIELD_LEN_BY_FORMAT() size,
+					or NULL when should not fetch
+					a longer prefix */
+	ulint		prefix_len,	/*!< prefix size to store in the
+					undo log */
+	ulint		zip_size,	/*!< compressed page size in bytes,
+					or 0 for uncompressed BLOB  */
+	const byte**	field,		/*!< in/out: the locally stored part of
+					the externally stored column */
+	ulint*		len)		/*!< in/out: length of field, in bytes */
+{
+	if (ext_buf) {
+		ut_a(prefix_len > 0);
+
+		/* If an ordering column is externally stored, we will
+		have to store a longer prefix of the field.  In this
+		case, write to the log a marker followed by the
+		original length and the real length of the field. */
+		ptr += mach_write_compressed(ptr, UNIV_EXTERN_STORAGE_FIELD);
+
+		ptr += mach_write_compressed(ptr, *len);
+
+		*field = trx_undo_page_fetch_ext(ext_buf, prefix_len, zip_size,
+						 *field, len);
+
+		ptr += mach_write_compressed(ptr, *len);
+	} else {
+		ptr += mach_write_compressed(ptr, UNIV_EXTERN_STORAGE_FIELD
+					     + *len);
+	}
+
+	return(ptr);
+}
+
+/**********************************************************************//**
+Reports in the undo log of an update or delete marking of a clustered index
+record.
+@return byte offset of the inserted undo log entry on the page if
+succeed, 0 if fail */
+static
+ulint
+trx_undo_page_report_modify(
+/*========================*/
+	page_t*		undo_page,	/*!< in: undo log page */
+	trx_t*		trx,		/*!< in: transaction */
+	dict_index_t*	index,		/*!< in: clustered index where update or
+					delete marking is done */
+	const rec_t*	rec,		/*!< in: clustered index record which
+					has NOT yet been modified */
+	const ulint*	offsets,	/*!< in: rec_get_offsets(rec, index) */
+	const upd_t*	update,		/*!< in: update vector which tells the
+					columns to be updated; in the case of
+					a delete, this should be set to NULL */
+	ulint		cmpl_info,	/*!< in: compiler info on secondary
+					index updates */
+	mtr_t*		mtr)		/*!< in: mtr */
+{
+	dict_table_t*	table;
+	ulint		first_free;
+	byte*		ptr;
+	const byte*	field;
+	ulint		flen;
+	ulint		col_no;
+	ulint		type_cmpl;
+	byte*		type_cmpl_ptr;
+	ulint		i;
+	trx_id_t	trx_id;
+	ibool		ignore_prefix = FALSE;
+	byte		ext_buf[REC_VERSION_56_MAX_INDEX_COL_LEN
+				+ BTR_EXTERN_FIELD_REF_SIZE];
+
+	ut_a(dict_index_is_clust(index));
+	ut_ad(rec_offs_validate(rec, index, offsets));
+	ut_ad(mach_read_from_2(undo_page + TRX_UNDO_PAGE_HDR
+			       + TRX_UNDO_PAGE_TYPE) == TRX_UNDO_UPDATE);
+	table = index->table;
+
+	first_free = mach_read_from_2(undo_page + TRX_UNDO_PAGE_HDR
+				      + TRX_UNDO_PAGE_FREE);
+	ptr = undo_page + first_free;
+
+	ut_ad(first_free <= UNIV_PAGE_SIZE);
+
+	if (trx_undo_left(undo_page, ptr) < 50) {
+
+		/* NOTE: the value 50 must be big enough so that the general
+		fields written below fit on the undo log page */
+
+		return(0);
+	}
+
+	/* Reserve 2 bytes for the pointer to the next undo log record */
+	ptr += 2;
+
+	/* Store first some general parameters to the undo log */
+
+	if (!update) {
+		ut_ad(!rec_get_deleted_flag(rec, dict_table_is_comp(table)));
+		type_cmpl = TRX_UNDO_DEL_MARK_REC;
+	} else if (rec_get_deleted_flag(rec, dict_table_is_comp(table))) {
+		type_cmpl = TRX_UNDO_UPD_DEL_REC;
+		/* We are about to update a delete marked record.
+		We don't typically need the prefix in this case unless
+		the delete marking is done by the same transaction
+		(which we check below). */
+		ignore_prefix = TRUE;
+	} else {
+		type_cmpl = TRX_UNDO_UPD_EXIST_REC;
+	}
+
+	type_cmpl |= cmpl_info * TRX_UNDO_CMPL_INFO_MULT;
+	type_cmpl_ptr = ptr;
+
+	*ptr++ = (byte) type_cmpl;
+	ptr += mach_ull_write_much_compressed(ptr, trx->undo_no);
+
+	ptr += mach_ull_write_much_compressed(ptr, table->id);
+
+	/*----------------------------------------*/
+	/* Store the state of the info bits */
+
+	*ptr++ = (byte) rec_get_info_bits(rec, dict_table_is_comp(table));
+
+	/* Store the values of the system columns */
+	field = rec_get_nth_field(rec, offsets,
+				  dict_index_get_sys_col_pos(
+					  index, DATA_TRX_ID), &flen);
+	ut_ad(flen == DATA_TRX_ID_LEN);
+
+	trx_id = trx_read_trx_id(field);
+
+	/* If it is an update of a delete marked record, then we are
+	allowed to ignore blob prefixes if the delete marking was done
+	by some other trx as it must have committed by now for us to
+	allow an over-write. */
+	if (ignore_prefix) {
+		ignore_prefix = (trx_id != trx->id);
+	}
+	ptr += mach_ull_write_compressed(ptr, trx_id);
+
+	field = rec_get_nth_field(rec, offsets,
+				  dict_index_get_sys_col_pos(
+					  index, DATA_ROLL_PTR), &flen);
+	ut_ad(flen == DATA_ROLL_PTR_LEN);
+
+	ptr += mach_ull_write_compressed(ptr, trx_read_roll_ptr(field));
+
+	/*----------------------------------------*/
+	/* Store then the fields required to uniquely determine the
+	record which will be modified in the clustered index */
+
+	for (i = 0; i < dict_index_get_n_unique(index); i++) {
+
+		field = rec_get_nth_field(rec, offsets, i, &flen);
+
+		/* The ordering columns must not be stored externally. */
+		ut_ad(!rec_offs_nth_extern(offsets, i));
+		ut_ad(dict_index_get_nth_col(index, i)->ord_part);
+
+		if (trx_undo_left(undo_page, ptr) < 5) {
+
+			return(0);
+		}
+
+		ptr += mach_write_compressed(ptr, flen);
+
+		if (flen != UNIV_SQL_NULL) {
+			if (trx_undo_left(undo_page, ptr) < flen) {
+
+				return(0);
+			}
+
+			ut_memcpy(ptr, field, flen);
+			ptr += flen;
+		}
+	}
+
+	/*----------------------------------------*/
+	/* Save to the undo log the old values of the columns to be updated. */
+
+	if (update) {
+		if (trx_undo_left(undo_page, ptr) < 5) {
+
+			return(0);
+		}
+
+		ptr += mach_write_compressed(ptr, upd_get_n_fields(update));
+
+		for (i = 0; i < upd_get_n_fields(update); i++) {
+
+			ulint	pos = upd_get_nth_field(update, i)->field_no;
+
+			/* Write field number to undo log */
+			if (trx_undo_left(undo_page, ptr) < 5) {
+
+				return(0);
+			}
+
+			ptr += mach_write_compressed(ptr, pos);
+
+			/* Save the old value of field */
+			field = rec_get_nth_field(rec, offsets, pos, &flen);
+
+			if (trx_undo_left(undo_page, ptr) < 15) {
+
+				return(0);
+			}
+
+			if (rec_offs_nth_extern(offsets, pos)) {
+				const dict_col_t*	col
+					= dict_index_get_nth_col(index, pos);
+				ulint			prefix_len
+					= dict_max_field_len_store_undo(
+						table, col);
+
+				ut_ad(prefix_len + BTR_EXTERN_FIELD_REF_SIZE
+				      <= sizeof ext_buf);
+
+				ptr = trx_undo_page_report_modify_ext(
+					ptr,
+					col->ord_part
+					&& !ignore_prefix
+					&& flen < REC_ANTELOPE_MAX_INDEX_COL_LEN
+					? ext_buf : NULL, prefix_len,
+					dict_table_zip_size(table),
+					&field, &flen);
+
+				/* Notify purge that it eventually has to
+				free the old externally stored field */
+
+				trx->update_undo->del_marks = TRUE;
+
+				*type_cmpl_ptr |= TRX_UNDO_UPD_EXTERN;
+			} else {
+				ptr += mach_write_compressed(ptr, flen);
+			}
+
+			if (flen != UNIV_SQL_NULL) {
+				if (trx_undo_left(undo_page, ptr) < flen) {
+
+					return(0);
+				}
+
+				ut_memcpy(ptr, field, flen);
+				ptr += flen;
+			}
+		}
+	}
+
+	/*----------------------------------------*/
+	/* In the case of a delete marking, and also in the case of an update
+	where any ordering field of any index changes, store the values of all
+	columns which occur as ordering fields in any index. This info is used
+	in the purge of old versions where we use it to build and search the
+	delete marked index records, to look if we can remove them from the
+	index tree. Note that starting from 4.0.14 also externally stored
+	fields can be ordering in some index. Starting from 5.2, we no longer
+	store REC_MAX_INDEX_COL_LEN first bytes to the undo log record,
+	but we can construct the column prefix fields in the index by
+	fetching the first page of the BLOB that is pointed to by the
+	clustered index. This works also in crash recovery, because all pages
+	(including BLOBs) are recovered before anything is rolled back. */
+
+	if (!update || !(cmpl_info & UPD_NODE_NO_ORD_CHANGE)) {
+		byte*	old_ptr = ptr;
+
+		trx->update_undo->del_marks = TRUE;
+
+		if (trx_undo_left(undo_page, ptr) < 5) {
+
+			return(0);
+		}
+
+		/* Reserve 2 bytes to write the number of bytes the stored
+		fields take in this undo record */
+
+		ptr += 2;
+
+		for (col_no = 0; col_no < dict_table_get_n_cols(table);
+		     col_no++) {
+
+			const dict_col_t*	col
+				= dict_table_get_nth_col(table, col_no);
+
+			if (col->ord_part) {
+				ulint	pos;
+
+				/* Write field number to undo log */
+				if (trx_undo_left(undo_page, ptr) < 5 + 15) {
+
+					return(0);
+				}
+
+				pos = dict_index_get_nth_col_pos(index,
+								 col_no);
+				ptr += mach_write_compressed(ptr, pos);
+
+				/* Save the old value of field */
+				field = rec_get_nth_field(rec, offsets, pos,
+							  &flen);
+
+				if (rec_offs_nth_extern(offsets, pos)) {
+					const dict_col_t*	col =
+						dict_index_get_nth_col(
+							index, pos);
+					ulint			prefix_len =
+						dict_max_field_len_store_undo(
+							table, col);
+
+					ut_a(prefix_len < sizeof ext_buf);
+
+					ptr = trx_undo_page_report_modify_ext(
+						ptr,
+						flen < REC_ANTELOPE_MAX_INDEX_COL_LEN
+						&& !ignore_prefix
+						? ext_buf : NULL, prefix_len,
+						dict_table_zip_size(table),
+						&field, &flen);
+				} else {
+					ptr += mach_write_compressed(
+						ptr, flen);
+				}
+
+				if (flen != UNIV_SQL_NULL) {
+					if (trx_undo_left(undo_page, ptr)
+					    < flen) {
+
+						return(0);
+					}
+
+					ut_memcpy(ptr, field, flen);
+					ptr += flen;
+				}
+			}
+		}
+
+		mach_write_to_2(old_ptr, ptr - old_ptr);
+	}
+
+	/*----------------------------------------*/
+	/* Write pointers to the previous and the next undo log records */
+	if (trx_undo_left(undo_page, ptr) < 2) {
+
+		return(0);
+	}
+
+	mach_write_to_2(ptr, first_free);
+	ptr += 2;
+	mach_write_to_2(undo_page + first_free, ptr - undo_page);
+
+	mach_write_to_2(undo_page + TRX_UNDO_PAGE_HDR + TRX_UNDO_PAGE_FREE,
+			ptr - undo_page);
+
+	/* Write to the REDO log about this change in the UNDO log */
+
+	trx_undof_page_add_undo_rec_log(undo_page, first_free,
+					ptr - undo_page, mtr);
+	return(first_free);
+}
+
+/**********************************************************************//**
+Reads from an undo log update record the system field values of the old
+version.
+@return	remaining part of undo log record after reading these values */
+UNIV_INTERN
+byte*
+trx_undo_update_rec_get_sys_cols(
+/*=============================*/
+	byte*		ptr,		/*!< in: remaining part of undo
+					log record after reading
+					general parameters */
+	trx_id_t*	trx_id,		/*!< out: trx id */
+	roll_ptr_t*	roll_ptr,	/*!< out: roll ptr */
+	ulint*		info_bits)	/*!< out: info bits state */
+{
+	/* Read the state of the info bits */
+	*info_bits = mach_read_from_1(ptr);
+	ptr += 1;
+
+	/* Read the values of the system columns */
+
+	*trx_id = mach_ull_read_compressed(ptr);
+	ptr += mach_ull_get_compressed_size(*trx_id);
+
+	*roll_ptr = mach_ull_read_compressed(ptr);
+	ptr += mach_ull_get_compressed_size(*roll_ptr);
+
+	return(ptr);
+}
+
+/**********************************************************************//**
+Reads from an update undo log record the number of updated fields.
+@return	remaining part of undo log record after reading this value */
+UNIV_INLINE
+byte*
+trx_undo_update_rec_get_n_upd_fields(
+/*=================================*/
+	byte*	ptr,	/*!< in: pointer to remaining part of undo log record */
+	ulint*	n)	/*!< out: number of fields */
+{
+	*n = mach_read_compressed(ptr);
+	ptr += mach_get_compressed_size(*n);
+
+	return(ptr);
+}
+
+/**********************************************************************//**
+Reads from an update undo log record a stored field number.
+@return	remaining part of undo log record after reading this value */
+UNIV_INLINE
+byte*
+trx_undo_update_rec_get_field_no(
+/*=============================*/
+	byte*	ptr,	/*!< in: pointer to remaining part of undo log record */
+	ulint*	field_no)/*!< out: field number */
+{
+	*field_no = mach_read_compressed(ptr);
+	ptr += mach_get_compressed_size(*field_no);
+
+	return(ptr);
+}
+
+/*******************************************************************//**
+Builds an update vector based on a remaining part of an undo log record.
+@return remaining part of the record, NULL if an error detected, which
+means that the record is corrupted */
+UNIV_INTERN
+byte*
+trx_undo_update_rec_get_update(
+/*===========================*/
+	byte*		ptr,	/*!< in: remaining part in update undo log
+				record, after reading the row reference
+				NOTE that this copy of the undo log record must
+				be preserved as long as the update vector is
+				used, as we do NOT copy the data in the
+				record! */
+	dict_index_t*	index,	/*!< in: clustered index */
+	ulint		type,	/*!< in: TRX_UNDO_UPD_EXIST_REC,
+				TRX_UNDO_UPD_DEL_REC, or
+				TRX_UNDO_DEL_MARK_REC; in the last case,
+				only trx id and roll ptr fields are added to
+				the update vector */
+	trx_id_t	trx_id,	/*!< in: transaction id from this undo record */
+	roll_ptr_t	roll_ptr,/*!< in: roll pointer from this undo record */
+	ulint		info_bits,/*!< in: info bits from this undo record */
+	trx_t*		trx,	/*!< in: transaction */
+	mem_heap_t*	heap,	/*!< in: memory heap from which the memory
+				needed is allocated */
+	upd_t**		upd)	/*!< out, own: update vector */
+{
+	upd_field_t*	upd_field;
+	upd_t*		update;
+	ulint		n_fields;
+	byte*		buf;
+	ulint		i;
+
+	ut_a(dict_index_is_clust(index));
+
+	if (type != TRX_UNDO_DEL_MARK_REC) {
+		ptr = trx_undo_update_rec_get_n_upd_fields(ptr, &n_fields);
+	} else {
+		n_fields = 0;
+	}
+
+	update = upd_create(n_fields + 2, heap);
+
+	update->info_bits = info_bits;
+
+	/* Store first trx id and roll ptr to update vector */
+
+	upd_field = upd_get_nth_field(update, n_fields);
+
+	buf = static_cast<byte*>(mem_heap_alloc(heap, DATA_TRX_ID_LEN));
+
+	trx_write_trx_id(buf, trx_id);
+
+	upd_field_set_field_no(upd_field,
+			       dict_index_get_sys_col_pos(index, DATA_TRX_ID),
+			       index, trx);
+	dfield_set_data(&(upd_field->new_val), buf, DATA_TRX_ID_LEN);
+
+	upd_field = upd_get_nth_field(update, n_fields + 1);
+
+	buf = static_cast<byte*>(mem_heap_alloc(heap, DATA_ROLL_PTR_LEN));
+
+	trx_write_roll_ptr(buf, roll_ptr);
+
+	upd_field_set_field_no(
+		upd_field, dict_index_get_sys_col_pos(index, DATA_ROLL_PTR),
+		index, trx);
+	dfield_set_data(&(upd_field->new_val), buf, DATA_ROLL_PTR_LEN);
+
+	/* Store then the updated ordinary columns to the update vector */
+
+	for (i = 0; i < n_fields; i++) {
+
+		byte*	field;
+		ulint	len;
+		ulint	field_no;
+		ulint	orig_len;
+
+		ptr = trx_undo_update_rec_get_field_no(ptr, &field_no);
+
+		if (field_no >= dict_index_get_n_fields(index)) {
+			fprintf(stderr,
+				"InnoDB: Error: trying to access"
+				" update undo rec field %lu in ",
+				(ulong) field_no);
+			dict_index_name_print(stderr, trx, index);
+			fprintf(stderr, "\n"
+				"InnoDB: but index has only %lu fields\n"
+				"InnoDB: Submit a detailed bug report"
+				" to http://bugs.mysql.com\n"
+				"InnoDB: Run also CHECK TABLE ",
+				(ulong) dict_index_get_n_fields(index));
+			ut_print_name(stderr, trx, TRUE, index->table_name);
+			fprintf(stderr, "\n"
+				"InnoDB: n_fields = %lu, i = %lu, ptr %p\n",
+				(ulong) n_fields, (ulong) i, ptr);
+			ut_ad(0);
+			*upd = NULL;
+			return(NULL);
+		}
+
+		upd_field = upd_get_nth_field(update, i);
+
+		upd_field_set_field_no(upd_field, field_no, index, trx);
+
+		ptr = trx_undo_rec_get_col_val(ptr, &field, &len, &orig_len);
+
+		upd_field->orig_len = orig_len;
+
+		if (len == UNIV_SQL_NULL) {
+			dfield_set_null(&upd_field->new_val);
+		} else if (len < UNIV_EXTERN_STORAGE_FIELD) {
+			dfield_set_data(&upd_field->new_val, field, len);
+		} else {
+			len -= UNIV_EXTERN_STORAGE_FIELD;
+
+			dfield_set_data(&upd_field->new_val, field, len);
+			dfield_set_ext(&upd_field->new_val);
+		}
+	}
+
+	*upd = update;
+
+	return(ptr);
+}
+
+/*******************************************************************//**
+Builds a partial row from an update undo log record, for purge.
+It contains the columns which occur as ordering in any index of the table.
+Any missing columns are indicated by col->mtype == DATA_MISSING.
+@return	pointer to remaining part of undo record */
+UNIV_INTERN
+byte*
+trx_undo_rec_get_partial_row(
+/*=========================*/
+	byte*		ptr,	/*!< in: remaining part in update undo log
+				record of a suitable type, at the start of
+				the stored index columns;
+				NOTE that this copy of the undo log record must
+				be preserved as long as the partial row is
+				used, as we do NOT copy the data in the
+				record! */
+	dict_index_t*	index,	/*!< in: clustered index */
+	dtuple_t**	row,	/*!< out, own: partial row */
+	ibool		ignore_prefix, /*!< in: flag to indicate if we
+				expect blob prefixes in undo. Used
+				only in the assertion. */
+	mem_heap_t*	heap)	/*!< in: memory heap from which the memory
+				needed is allocated */
+{
+	const byte*	end_ptr;
+	ulint		row_len;
+
+	ut_ad(index);
+	ut_ad(ptr);
+	ut_ad(row);
+	ut_ad(heap);
+	ut_ad(dict_index_is_clust(index));
+
+	row_len = dict_table_get_n_cols(index->table);
+
+	*row = dtuple_create(heap, row_len);
+
+	/* Mark all columns in the row uninitialized, so that
+	we can distinguish missing fields from fields that are SQL NULL. */
+	for (ulint i = 0; i < row_len; i++) {
+		dfield_get_type(dtuple_get_nth_field(*row, i))
+			->mtype = DATA_MISSING;
+	}
+
+	end_ptr = ptr + mach_read_from_2(ptr);
+	ptr += 2;
+
+	while (ptr != end_ptr) {
+		dfield_t*		dfield;
+		byte*			field;
+		ulint			field_no;
+		const dict_col_t*	col;
+		ulint			col_no;
+		ulint			len;
+		ulint			orig_len;
+
+		ptr = trx_undo_update_rec_get_field_no(ptr, &field_no);
+
+		col = dict_index_get_nth_col(index, field_no);
+		col_no = dict_col_get_no(col);
+
+		ptr = trx_undo_rec_get_col_val(ptr, &field, &len, &orig_len);
+
+		dfield = dtuple_get_nth_field(*row, col_no);
+		dict_col_copy_type(
+			dict_table_get_nth_col(index->table, col_no),
+			dfield_get_type(dfield));
+		dfield_set_data(dfield, field, len);
+
+		if (len != UNIV_SQL_NULL
+		    && len >= UNIV_EXTERN_STORAGE_FIELD) {
+			dfield_set_len(dfield,
+				       len - UNIV_EXTERN_STORAGE_FIELD);
+			dfield_set_ext(dfield);
+			/* If the prefix of this column is indexed,
+			ensure that enough prefix is stored in the
+			undo log record. */
+			if (!ignore_prefix && col->ord_part) {
+				ut_a(dfield_get_len(dfield)
+				     >= BTR_EXTERN_FIELD_REF_SIZE);
+				ut_a(dict_table_get_format(index->table)
+				     >= UNIV_FORMAT_B
+				     || dfield_get_len(dfield)
+				     >= REC_ANTELOPE_MAX_INDEX_COL_LEN
+				     + BTR_EXTERN_FIELD_REF_SIZE);
+			}
+		}
+	}
+
+	return(ptr);
+}
+#endif /* !UNIV_HOTBACKUP */
+
+/***********************************************************************//**
+Erases the unused undo log page end.
+@return TRUE if the page contained something, FALSE if it was empty */
+static __attribute__((nonnull))
+ibool
+trx_undo_erase_page_end(
+/*====================*/
+	page_t*	undo_page,	/*!< in/out: undo page whose end to erase */
+	mtr_t*	mtr)		/*!< in/out: mini-transaction */
+{
+	ulint	first_free;
+
+	first_free = mach_read_from_2(undo_page + TRX_UNDO_PAGE_HDR
+				      + TRX_UNDO_PAGE_FREE);
+	memset(undo_page + first_free, 0xff,
+	       (UNIV_PAGE_SIZE - FIL_PAGE_DATA_END) - first_free);
+
+	mlog_write_initial_log_record(undo_page, MLOG_UNDO_ERASE_END, mtr);
+	return(first_free != TRX_UNDO_PAGE_HDR + TRX_UNDO_PAGE_HDR_SIZE);
+}
+
+/***********************************************************//**
+Parses a redo log record of erasing of an undo page end.
+@return	end of log record or NULL */
+UNIV_INTERN
+byte*
+trx_undo_parse_erase_page_end(
+/*==========================*/
+	byte*	ptr,	/*!< in: buffer */
+	byte*	end_ptr __attribute__((unused)), /*!< in: buffer end */
+	page_t*	page,	/*!< in: page or NULL */
+	mtr_t*	mtr)	/*!< in: mtr or NULL */
+{
+	ut_ad(ptr && end_ptr);
+
+	if (page == NULL) {
+
+		return(ptr);
+	}
+
+	trx_undo_erase_page_end(page, mtr);
+
+	return(ptr);
+}
+
+#ifndef UNIV_HOTBACKUP
+/***********************************************************************//**
+Writes information to an undo log about an insert, update, or a delete marking
+of a clustered index record. This information is used in a rollback of the
+transaction and in consistent reads that must look to the history of this
+transaction.
+@return	DB_SUCCESS or error code */
+UNIV_INTERN
+dberr_t
+trx_undo_report_row_operation(
+/*==========================*/
+	ulint		flags,		/*!< in: if BTR_NO_UNDO_LOG_FLAG bit is
+					set, does nothing */
+	ulint		op_type,	/*!< in: TRX_UNDO_INSERT_OP or
+					TRX_UNDO_MODIFY_OP */
+	que_thr_t*	thr,		/*!< in: query thread */
+	dict_index_t*	index,		/*!< in: clustered index */
+	const dtuple_t*	clust_entry,	/*!< in: in the case of an insert,
+					index entry to insert into the
+					clustered index, otherwise NULL */
+	const upd_t*	update,		/*!< in: in the case of an update,
+					the update vector, otherwise NULL */
+	ulint		cmpl_info,	/*!< in: compiler info on secondary
+					index updates */
+	const rec_t*	rec,		/*!< in: in case of an update or delete
+					marking, the record in the clustered
+					index, otherwise NULL */
+	const ulint*	offsets,	/*!< in: rec_get_offsets(rec) */
+	roll_ptr_t*	roll_ptr)	/*!< out: rollback pointer to the
+					inserted undo log record,
+					0 if BTR_NO_UNDO_LOG
+					flag was specified */
+{
+	trx_t*		trx;
+	trx_undo_t*	undo;
+	ulint		page_no;
+	buf_block_t*	undo_block;
+	trx_rseg_t*	rseg;
+	mtr_t		mtr;
+	dberr_t		err		= DB_SUCCESS;
+#ifdef UNIV_DEBUG
+	int		loop_count	= 0;
+#endif /* UNIV_DEBUG */
+
+	ut_ad(!srv_read_only_mode);
+	ut_a(dict_index_is_clust(index));
+	ut_ad(!rec || rec_offs_validate(rec, index, offsets));
+
+	if (flags & BTR_NO_UNDO_LOG_FLAG) {
+
+		*roll_ptr = 0;
+
+		return(DB_SUCCESS);
+	}
+
+	ut_ad(thr);
+	ut_ad((op_type != TRX_UNDO_INSERT_OP)
+	      || (clust_entry && !update && !rec));
+
+	trx = thr_get_trx(thr);
+
+	/* This table is visible only to the session that created it. */
+	if (trx->read_only) {
+		ut_ad(!srv_read_only_mode);
+		/* MySQL should block writes to non-temporary tables. */
+		ut_a(DICT_TF2_FLAG_IS_SET(index->table, DICT_TF2_TEMPORARY));
+		if (trx->rseg == 0) {
+			trx_assign_rseg(trx);
+		}
+	}
+
+	rseg = trx->rseg;
+
+	mtr_start(&mtr);
+	mutex_enter(&trx->undo_mutex);
+
+	/* If the undo log is not assigned yet, assign one */
+
+	switch (op_type) {
+	case TRX_UNDO_INSERT_OP:
+		undo = trx->insert_undo;
+
+		if (undo == NULL) {
+
+			err = trx_undo_assign_undo(trx, TRX_UNDO_INSERT);
+			undo = trx->insert_undo;
+
+			if (undo == NULL) {
+				/* Did not succeed */
+				ut_ad(err != DB_SUCCESS);
+				goto err_exit;
+			}
+
+			ut_ad(err == DB_SUCCESS);
+		}
+		break;
+	default:
+		ut_ad(op_type == TRX_UNDO_MODIFY_OP);
+
+		undo = trx->update_undo;
+
+		if (undo == NULL) {
+			err = trx_undo_assign_undo(trx, TRX_UNDO_UPDATE);
+			undo = trx->update_undo;
+
+			if (undo == NULL) {
+				/* Did not succeed */
+				ut_ad(err != DB_SUCCESS);
+				goto err_exit;
+			}
+		}
+
+		ut_ad(err == DB_SUCCESS);
+	}
+
+	page_no = undo->last_page_no;
+	undo_block = buf_page_get_gen(
+		undo->space, undo->zip_size, page_no, RW_X_LATCH,
+		undo->guess_block, BUF_GET, __FILE__, __LINE__, &mtr);
+	buf_block_dbg_add_level(undo_block, SYNC_TRX_UNDO_PAGE);
+
+	do {
+		page_t*		undo_page;
+		ulint		offset;
+
+		undo_page = buf_block_get_frame(undo_block);
+		ut_ad(page_no == buf_block_get_page_no(undo_block));
+
+		switch (op_type) {
+		case TRX_UNDO_INSERT_OP:
+			offset = trx_undo_page_report_insert(
+				undo_page, trx, index, clust_entry, &mtr);
+			break;
+		default:
+			ut_ad(op_type == TRX_UNDO_MODIFY_OP);
+			offset = trx_undo_page_report_modify(
+				undo_page, trx, index, rec, offsets, update,
+				cmpl_info, &mtr);
+		}
+
+		if (UNIV_UNLIKELY(offset == 0)) {
+			/* The record did not fit on the page. We erase the
+			end segment of the undo log page and write a log
+			record of it: this is to ensure that in the debug
+			version the replicate page constructed using the log
+			records stays identical to the original page */
+
+			if (!trx_undo_erase_page_end(undo_page, &mtr)) {
+				/* The record did not fit on an empty
+				undo page. Discard the freshly allocated
+				page and return an error. */
+
+				/* When we remove a page from an undo
+				log, this is analogous to a
+				pessimistic insert in a B-tree, and we
+				must reserve the counterpart of the
+				tree latch, which is the rseg
+				mutex. We must commit the mini-transaction
+				first, because it may be holding lower-level
+				latches, such as SYNC_FSP and SYNC_FSP_PAGE. */
+
+				mtr_commit(&mtr);
+				mtr_start(&mtr);
+
+				mutex_enter(&rseg->mutex);
+				trx_undo_free_last_page(trx, undo, &mtr);
+				mutex_exit(&rseg->mutex);
+
+				err = DB_UNDO_RECORD_TOO_BIG;
+				goto err_exit;
+			}
+
+			mtr_commit(&mtr);
+		} else {
+			/* Success */
+
+			mtr_commit(&mtr);
+
+			undo->empty = FALSE;
+			undo->top_page_no = page_no;
+			undo->top_offset  = offset;
+			undo->top_undo_no = trx->undo_no;
+			undo->guess_block = undo_block;
+
+			trx->undo_no++;
+
+			mutex_exit(&trx->undo_mutex);
+
+			*roll_ptr = trx_undo_build_roll_ptr(
+				op_type == TRX_UNDO_INSERT_OP,
+				rseg->id, page_no, offset);
+			return(DB_SUCCESS);
+		}
+
+		ut_ad(page_no == undo->last_page_no);
+
+		/* We have to extend the undo log by one page */
+
+		ut_ad(++loop_count < 2);
+		mtr_start(&mtr);
+
+		/* When we add a page to an undo log, this is analogous to
+		a pessimistic insert in a B-tree, and we must reserve the
+		counterpart of the tree latch, which is the rseg mutex. */
+
+		mutex_enter(&rseg->mutex);
+		undo_block = trx_undo_add_page(trx, undo, &mtr);
+		mutex_exit(&rseg->mutex);
+
+		page_no = undo->last_page_no;
+	} while (undo_block != NULL);
+
+	/* Did not succeed: out of space */
+	err = DB_OUT_OF_FILE_SPACE;
+
+err_exit:
+	mutex_exit(&trx->undo_mutex);
+	mtr_commit(&mtr);
+	return(err);
+}
+
+/*============== BUILDING PREVIOUS VERSION OF A RECORD ===============*/
+
+/******************************************************************//**
+Copies an undo record to heap. This function can be called if we know that
+the undo log record exists.
+@return	own: copy of the record */
+UNIV_INTERN
+trx_undo_rec_t*
+trx_undo_get_undo_rec_low(
+/*======================*/
+	roll_ptr_t	roll_ptr,	/*!< in: roll pointer to record */
+	mem_heap_t*	heap)		/*!< in: memory heap where copied */
+{
+	trx_undo_rec_t*	undo_rec;
+	ulint		rseg_id;
+	ulint		page_no;
+	ulint		offset;
+	const page_t*	undo_page;
+	trx_rseg_t*	rseg;
+	ibool		is_insert;
+	mtr_t		mtr;
+
+	trx_undo_decode_roll_ptr(roll_ptr, &is_insert, &rseg_id, &page_no,
+				 &offset);
+	rseg = trx_rseg_get_on_id(rseg_id);
+
+	mtr_start(&mtr);
+
+	undo_page = trx_undo_page_get_s_latched(rseg->space, rseg->zip_size,
+						page_no, &mtr);
+
+	undo_rec = trx_undo_rec_copy(undo_page + offset, heap);
+
+	mtr_commit(&mtr);
+
+	return(undo_rec);
+}
+
+/******************************************************************//**
+Copies an undo record to heap.
+
+NOTE: the caller must have latches on the clustered index page.
+
+@retval true if the undo log has been
+truncated and we cannot fetch the old version
+@retval false if the undo log record is available  */
+static __attribute__((nonnull, warn_unused_result))
+bool
+trx_undo_get_undo_rec(
+/*==================*/
+	roll_ptr_t	roll_ptr,	/*!< in: roll pointer to record */
+	trx_id_t	trx_id,		/*!< in: id of the trx that generated
+					the roll pointer: it points to an
+					undo log of this transaction */
+	trx_undo_rec_t**undo_rec,	/*!< out, own: copy of the record */
+	mem_heap_t*	heap)		/*!< in: memory heap where copied */
+{
+	bool		missing_history;
+
+	rw_lock_s_lock(&purge_sys->latch);
+	missing_history = read_view_sees_trx_id(purge_sys->view, trx_id);
+
+	if (!missing_history) {
+		*undo_rec = trx_undo_get_undo_rec_low(roll_ptr, heap);
+	}
+
+	rw_lock_s_unlock(&purge_sys->latch);
+
+	return(missing_history);
+}
+
+#ifdef UNIV_DEBUG
+#define ATTRIB_USED_ONLY_IN_DEBUG
+#else /* UNIV_DEBUG */
+#define ATTRIB_USED_ONLY_IN_DEBUG	__attribute__((unused))
+#endif /* UNIV_DEBUG */
+
+/*******************************************************************//**
+Build a previous version of a clustered index record. The caller must
+hold a latch on the index page of the clustered index record.
+@retval true if previous version was built, or if it was an insert
+or the table has been rebuilt
+@retval false if the previous version is earlier than purge_view,
+which means that it may have been removed */
+UNIV_INTERN
+bool
+trx_undo_prev_version_build(
+/*========================*/
+	const rec_t*	index_rec ATTRIB_USED_ONLY_IN_DEBUG,
+				/*!< in: clustered index record in the
+				index tree */
+	mtr_t*		index_mtr ATTRIB_USED_ONLY_IN_DEBUG,
+				/*!< in: mtr which contains the latch to
+				index_rec page and purge_view */
+	const rec_t*	rec,	/*!< in: version of a clustered index record */
+	dict_index_t*	index,	/*!< in: clustered index */
+	ulint*		offsets,/*!< in/out: rec_get_offsets(rec, index) */
+	mem_heap_t*	heap,	/*!< in: memory heap from which the memory
+				needed is allocated */
+	rec_t**		old_vers)/*!< out, own: previous version, or NULL if
+				rec is the first inserted version, or if
+				history data has been deleted (an error),
+				or if the purge COULD have removed the version
+				though it has not yet done so */
+{
+	trx_undo_rec_t*	undo_rec	= NULL;
+	dtuple_t*	entry;
+	trx_id_t	rec_trx_id;
+	ulint		type;
+	undo_no_t	undo_no;
+	table_id_t	table_id;
+	trx_id_t	trx_id;
+	roll_ptr_t	roll_ptr;
+	upd_t*		update;
+	byte*		ptr;
+	ulint		info_bits;
+	ulint		cmpl_info;
+	bool		dummy_extern;
+	byte*		buf;
+#ifdef UNIV_SYNC_DEBUG
+	ut_ad(!rw_lock_own(&purge_sys->latch, RW_LOCK_SHARED));
+#endif /* UNIV_SYNC_DEBUG */
+	ut_ad(mtr_memo_contains_page(index_mtr, index_rec, MTR_MEMO_PAGE_S_FIX)
+	      || mtr_memo_contains_page(index_mtr, index_rec,
+					MTR_MEMO_PAGE_X_FIX));
+	ut_ad(rec_offs_validate(rec, index, offsets));
+	ut_a(dict_index_is_clust(index));
+
+	roll_ptr = row_get_rec_roll_ptr(rec, index, offsets);
+
+	*old_vers = NULL;
+
+	if (trx_undo_roll_ptr_is_insert(roll_ptr)) {
+		/* The record rec is the first inserted version */
+		return(true);
+	}
+
+	rec_trx_id = row_get_rec_trx_id(rec, index, offsets);
+
+	if (trx_undo_get_undo_rec(roll_ptr, rec_trx_id, &undo_rec, heap)) {
+		/* The undo record may already have been purged,
+		during purge or semi-consistent read. */
+		return(false);
+	}
+
+	ptr = trx_undo_rec_get_pars(undo_rec, &type, &cmpl_info,
+				    &dummy_extern, &undo_no, &table_id);
+
+	if (table_id != index->table->id) {
+		/* The table should have been rebuilt, but purge has
+		not yet removed the undo log records for the
+		now-dropped old table (table_id). */
+		return(true);
+	}
+
+	ptr = trx_undo_update_rec_get_sys_cols(ptr, &trx_id, &roll_ptr,
+					       &info_bits);
+
+	/* (a) If a clustered index record version is such that the
+	trx id stamp in it is bigger than purge_sys->view, then the
+	BLOBs in that version are known to exist (the purge has not
+	progressed that far);
+
+	(b) if the version is the first version such that trx id in it
+	is less than purge_sys->view, and it is not delete-marked,
+	then the BLOBs in that version are known to exist (the purge
+	cannot have purged the BLOBs referenced by that version
+	yet).
+
+	This function does not fetch any BLOBs.  The callers might, by
+	possibly invoking row_ext_create() via row_build().  However,
+	they should have all needed information in the *old_vers
+	returned by this function.  This is because *old_vers is based
+	on the transaction undo log records.  The function
+	trx_undo_page_fetch_ext() will write BLOB prefixes to the
+	transaction undo log that are at least as long as the longest
+	possible column prefix in a secondary index.  Thus, secondary
+	index entries for *old_vers can be constructed without
+	dereferencing any BLOB pointers. */
+
+	ptr = trx_undo_rec_skip_row_ref(ptr, index);
+
+	ptr = trx_undo_update_rec_get_update(ptr, index, type, trx_id,
+					     roll_ptr, info_bits,
+					     NULL, heap, &update);
+	ut_a(ptr);
+
+# if defined UNIV_DEBUG || defined UNIV_BLOB_LIGHT_DEBUG
+	ut_a(!rec_offs_any_null_extern(rec, offsets));
+# endif /* UNIV_DEBUG || UNIV_BLOB_LIGHT_DEBUG */
+
+	if (row_upd_changes_field_size_or_external(index, offsets, update)) {
+		ulint	n_ext;
+
+		/* We should confirm the existence of disowned external data,
+		if the previous version record is delete marked. If the trx_id
+		of the previous record is seen by purge view, we should treat
+		it as missing history, because the disowned external data
+		might be purged already.
+
+		The inherited external data (BLOBs) can be freed (purged)
+		after trx_id was committed, provided that no view was started
+		before trx_id. If the purge view can see the committed
+		delete-marked record by trx_id, no transactions need to access
+		the BLOB. */
+
+		/* the row_upd_changes_disowned_external(update) call could be
+		omitted, but the synchronization on purge_sys->latch is likely
+		more expensive. */
+
+		if ((update->info_bits & REC_INFO_DELETED_FLAG)
+		    && row_upd_changes_disowned_external(update)) {
+			bool	missing_extern;
+
+			rw_lock_s_lock(&purge_sys->latch);
+			missing_extern = read_view_sees_trx_id(purge_sys->view,
+							       trx_id);
+			rw_lock_s_unlock(&purge_sys->latch);
+
+			if (missing_extern) {
+				/* treat as a fresh insert, not to
+				cause assertion error at the caller. */
+				return(true);
+			}
+		}
+
+		/* We have to set the appropriate extern storage bits in the
+		old version of the record: the extern bits in rec for those
+		fields that update does NOT update, as well as the bits for
+		those fields that update updates to become externally stored
+		fields. Store the info: */
+
+		entry = row_rec_to_index_entry(
+			rec, index, offsets, &n_ext, heap);
+		n_ext += btr_push_update_extern_fields(entry, update, heap);
+		/* The page containing the clustered index record
+		corresponding to entry is latched in mtr.  Thus the
+		following call is safe. */
+		row_upd_index_replace_new_col_vals(entry, index, update, heap);
+
+		buf = static_cast<byte*>(
+			mem_heap_alloc(
+				heap,
+				rec_get_converted_size(index, entry, n_ext)));
+
+		*old_vers = rec_convert_dtuple_to_rec(buf, index,
+						      entry, n_ext);
+	} else {
+		buf = static_cast<byte*>(
+			mem_heap_alloc(heap, rec_offs_size(offsets)));
+
+		*old_vers = rec_copy(buf, rec, offsets);
+		rec_offs_make_valid(*old_vers, index, offsets);
+		row_upd_rec_in_place(*old_vers, index, offsets, update, NULL);
+	}
+
+	return(true);
+}
+#endif /* !UNIV_HOTBACKUP */